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  <meta charset="UTF-8">
  <title>基本数据类型定义判断</title>
  <script type="text/javascript">
	var a= 123;
	document.write("变量a的数据类型为："+(typeof a));
	
	document.write("<br/>");

	var b = 23.3;
	document.write("变量b的数据类型为："+(typeof b));
	document.write("<br/>");

	var c = "hello";
	document.write("变量c的数据类型为："+(typeof c));
	document.write("<br/>");

	var d = true; //true，false真假,布尔类型
	document.write("变量d的数据类型为："+(typeof d));
	document.write("<br/>");

	var e = 1>2;  //判断都是返回的布尔类型
	document.write("变量e的数据类型为："+(typeof e));
	document.write("<br/>");

	var f;
	document.write("变量f的数据类型为："+(typeof f)); //undefined未定义
	document.write("<br/>");

	var n = null;
	document.write("变量n的数据类型为："+(typeof n));  //object
	document.write("<br/>");
  </script>
 </head>
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 </body>
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